The use of drill guides is common for making holes with a portable or hand drill. If a drill guide, or other means such as a drill column, is not used for guiding the movement of the drill in the perforation, holes are uneven and, therefore, this usually results in a variation in gradient with respect to the vertical needed on the surface to be perforated.
Furthermore, by using the drill guide one ensures that the drill bit does not move from the initial point of perforation until one starts drilling.
The drill guide consists of a flat template of a certain thickness, on which there is a series of through holes corresponding to the diameters of the drill bits that may be used. On placing the drill guide on the surface to be perforated, each through hole provides a guide-route for the tip of the drill bit that is almost perpendicular to the surface to be perforated, thus improving the quality of the hole made.
The drill guide also has a feature whereby the template may be used with a manipulation handle to firmly support it. In both cases, the guide has a hole for every possible drill bit diameter that may be used. The guide is therefore large, bulky and heavy if only one of the guide holes is to be used.
In certain situations, the drill bit must be cooled when the material of the object to be perforated is very hard and is difficult to drill. In such situations, the drill bit heats up through friction and it is advisable to cool it down in order to avoid the high temperatures that reduce the performance of the tool. This operation is carried out by directly applying fluid, such as compressed air or water, onto the drill bit and the hole. The use of water is very effective, but dirty and awkward if the amount of water supplied is not controlled. Furthermore, the drill guide must be detached and the water applied directly. Otherwise the drill bit must be removed and cooled down separately. In either case, the process is inconvenient and hinders attaining a good quality finish of the hole to be drilled.